So the next time you notice he's covering up another mistake instead of copping to it, you'll need to charge him a price, so to speak, for his deceitfulness. And the purpose of that likely heavy toll is to reveal to him that he's been found out. Talk with him privately, and suggest that sometimes we all make mistakes and often feel embarrassed by them. But also let him know that when he fails to admit an error and covers it up, it results in the opposite of the outcome he probably desires – namely, his easily detectable dissembling lowers others' opinions about him, and thereby compounds his miscues.

Your co-worker may be uncomfortable hearing this, so it's important to emphasize to him that we all are imperfect and therefore make mistakes. Give him an example or two of goofs you've made, and how owning up to them was a better alternative than evading them. Let him know that it's smarter in your corporate culture to openly own your missteps than to cover them up. Attaching a price to his behavior – in this case, confronting him – combined with a sincere effort to help set him straight just might make him see that honesty is indeed the best policy.E